Typically, a person who goes shopping attends several stores to compare assortment of goods, prices and availability of desired products. Handheld digital devices, e.g. smartphones, have become efficient assistants for performing shopping. The person may, for example, create a list of products to buy and may save this list on a smartphone. When being at the store, the smartphone may be used to scan product barcodes to retrieve product information or perform payment based on payment information encoded in the product barcodes. However, long-term constant holding of the smartphone in a hand may cause inconvenience to the person who performs shopping at the store. For example, when the person wants to take a big size product, the person firstly needs to empty his hands and, therefore, to put the smartphone into his pocket. After inspecting the desired product, the person will need to get the smartphone out of the pocket in order to scan a barcode of the desired product or to see what products left in the list of products to buy.
In addition to that, when using a smartphone in a store, a person needs to repeatedly look at a display of the smartphone, for example, to check a list of products stored on the smartphone or to read product information retrieved from a product barcode. Therefore, time spent on shopping may increase.